CCNA Exploration 1 Chapter 7

A physical topology is a type of drawing that provides a graphic representation of the exact location of the company's network wiring and equipment in the building. It shows the physical layout and connections of devices such as routers, switches, and cables. This drawing helps the network administrator to understand and manage the physical infrastructure of the network, including the placement of equipment and the paths of cables.

The primary purpose of the trailer in a data link layer frame is to support frame error detection. The trailer contains a checksum or cyclic redundancy check (CRC) value that is used to verify the integrity of the frame during transmission. By comparing the calculated checksum with the one in the trailer, errors can be detected, such as missing or flipped bits. This allows the receiving device to identify if any errors occurred during transmission and request retransmission if necessary.

The Media Access Control (MAC) sublayer of the data link layer prepares a signal to be transmitted at the physical layer. It is responsible for controlling access to the physical transmission medium, such as Ethernet cables or wireless channels. The MAC sublayer handles tasks such as framing, addressing, and error checking before passing the signal to the physical layer for transmission.

The purpose of the preamble in an Ethernet frame is to provide timing synchronization with alternating patterns of ones and zeros. This allows the receiving device to synchronize its clock with the sender's clock and accurately decode the incoming data. The preamble helps in establishing the correct timing for the data transmission and ensures that the receiver can accurately interpret the bits being transmitted.

The correct answer is "Network 1 uses CSMA/CD and Network 3 uses CSMA/CA." This is because the question asks for the media access control methods used by the networks in the exhibit. CSMA/CD (Carrier Sense Multiple Access/Collision Detection) is a media access control method used by Network 1, while CSMA/CA (Carrier Sense Multiple Access/Collision Avoidance) is used by Network 3.

Host A will place the MAC address 00-0c-85-cf-65-c0 in the destination address field of Ethernet frames destined for http://www.server.

The data link layer provides for the exchange of data over a common local media. This layer is responsible for establishing and terminating connections between nodes on a network, as well as for controlling the flow of data and detecting and correcting errors in the transmission. It also handles the addressing of devices on the network and the encapsulation and de-encapsulation of data packets. Overall, the data link layer ensures reliable and efficient communication between devices connected to the same local network.

The primary purpose of encapsulating packets into frames is to facilitate the entry and exit of data on media. Encapsulation involves adding a header and a trailer to the packet, creating a frame. This frame is then transmitted over the network media. The header contains information such as source and destination addresses, while the trailer is used for error checking. By encapsulating packets into frames, the data can be efficiently transmitted and received by devices on the network media.

The correct answer is that logical topologies consist of virtual connections between nodes. This means that the way nodes are connected in a logical topology does not necessarily reflect the physical layout of the network. Logical topologies are concerned with how data is transmitted between nodes and can be different from the physical topology, which focuses on the physical arrangement of devices and cables. The physical topology determines how frames are transferred, while the logical topology determines the logical paths through which data travels.

The given exhibit is not available, so it is difficult to provide a specific explanation for the answer. However, in general, the number of unique CRC calculations depends on the number of different paths or routes the traffic can take from the PC to the laptop. If there are 8 different paths, then 8 unique CRC calculations would be needed.

When a device is moved from one network or subnet to another, two facts are true. First, the device will still operate at the same Layer 2 address. This means that the MAC address of the device remains the same even after the move. Second, the Layer 3 address must be reassigned to allow communications to the new network. This means that the IP address of the device needs to be changed to be compatible with the new network or subnet.

Layer 2 may identify devices by a physical address burned into the network card. This is true because Layer 2, also known as the Data Link Layer, uses MAC addresses to identify devices on a local network. These MAC addresses are unique and are assigned to the network card during manufacturing.

Layer 3 represents a hierarchical addressing scheme. This is true because Layer 3, also known as the Network Layer, uses IP addresses to provide a hierarchical addressing scheme. IP addresses are hierarchical in nature, with different levels of network and host portions, allowing for efficient routing and addressing in large networks.

A characteristic of a logical point-to-point topology is that the media access control protocol can be very simple. In a point-to-point topology, there is a direct connection between two nodes, allowing for a dedicated communication channel. This eliminates the need for complex media access control protocols, as there is no contention for the network resources. Each node can transmit data without interference, resulting in a simpler protocol.

In a logical token-passing topology, computers are allowed to transmit data only when they possess a token. This means that each computer on the network must wait for its turn to possess the token before it can transmit data. Additionally, electronic tokens are passed sequentially to each other, ensuring that each computer gets a fair chance to transmit data. This topology helps regulate network usage on a first come, first serve basis and ensures that data from a host is received by all other hosts. However, it does not mention anything about high collision rates, so it cannot be concluded that token passing networks have problems with high collision rates.

The frame is being sent from the PC to the laptop, so the source MAC address will be the MAC address of the PC. As the frame leaves RouterB, the source MAC address will be the MAC address of the outgoing interface on RouterB, which is Fa0/1. Similarly, the source IP address will be the IP address of the PC. Therefore, the source MAC address will be Fa0/1 on RouterB and the source IP address will be the IP address of the PC.

The method of media access control is determined by two factors: media sharing and logical topology. Media sharing refers to how multiple devices share the same physical medium, such as Ethernet cables or wireless frequencies. The method used to allocate access to the media among the devices is crucial in preventing collisions and ensuring efficient communication. Logical topology, on the other hand, defines how devices are connected and communicate with each other in a network. Different logical topologies, such as bus, ring, or star, may require different methods of media access control to facilitate communication effectively.

Contention-based media access is a method used in shared media networks where multiple devices compete for access to the medium. In this approach, there is no predetermined order for transmitting data, making it non-deterministic. This lack of determinism allows for flexibility and adaptability in the network. Additionally, contention-based media access typically has less overhead compared to other methods, as it does not require complex protocols or token management. However, collisions can occur in contention-based media access when multiple devices attempt to transmit simultaneously, leading to a decrease in network performance. Therefore, the correct options for properties of contention-based media access in this question are non-deterministic, less overhead, and collisions exist.

Ethernet Layer 2 addresses, also known as MAC addresses, are 48 binary bits in length. They are considered physical addresses because they are assigned to the network interface card (NIC) of a device. These addresses are generally represented in hexadecimal format for easier readability.

When implementing a Layer 2 protocol in a network, three factors that should be considered are the geographic scope of the network, the physical layer implementation, and the number of hosts to be interconnected. The geographic scope of the network is important because it determines the distance over which the Layer 2 protocol needs to operate effectively. The physical layer implementation is crucial as it determines the type of media and hardware that will be used for communication. The number of hosts to be interconnected is significant because it affects the scalability and performance of the Layer 2 protocol.

CSMA/CD is a media access control method used in Ethernet networks. It stands for Carrier Sense Multiple Access with Collision Detection. This method allows devices to listen to the network before transmitting data, and if the network is clear, they can send their data. If two devices attempt to transmit at the same time and a collision occurs, they both stop transmitting and wait for a random amount of time before trying again. This helps to minimize data collisions and ensure fair access to the network. Data Link layer protocols, such as Ethernet, define the rules for accessing different types of media, including how data frames are placed on the media.